Piston pump

ABSTRACT

A piston pump ( 10 ) for supplying pressure fluid into at least one vehicle brake, into a master cylinder, into a pressure fluid reservoir, or into a pressure fluid accumulator of a controlled vehicle brake system, is integrated into an accommodating member ( 3 ) in a simple and space-saving manner. A plurality of valve seats ( 38, 54 ) of non-return valves ( 32, 33, 36, 37 ) are kept as free as possible from pressing or attaching forces in that a sleeve ( 18, 19 ) has a radial flange for being secured in position between a closing member ( 52 ) and the accommodating member ( 3 ).

BACKGROUND OF THE INVENTION

The present invention relates to a piston pump for supplying pressurefluid into at least one vehicle brake, into a master cylinder, into apressure fluid reservoir or into a pressure fluid accumulator of acontrolled vehicle brake system.

A piston pump of this type is e.g. disclosed in DE 100 22 811 A1 andcomprises, among others, a sleeve retained in a stepped bore. Thissleeve is pressed into the stepped bore by a closing member that abutsaxially on a bottom of the sleeve. It is disadvantageous in this type ofconstruction that the pressing and attaching forces introduced into thesleeve may cause a deformation of a seat for a non-return valve. Thisjeopardizes the operational safety of the vehicle brake system.

A generic piston pump is described in DE 197 53 083 A1. A closing memberbears in an axial direction directly against the sleeve, pressing itaxially against a bore step. The forces introduced through the sleeveand a conical abutment surface of the sleeve in the area of thenon-return valve can cause a deformation of the sleeve in the area ofthe valve seat.

In view of the above, an object of the invention is to disclose a meanspermitting an integration of a piston-pump subassembly into anaccommodating member, while in particular valve seats of non-returnvalves can be retained so as to be free from pressing or attachingforces being due to the assembly and from resultant deformations.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved in that the sleeveincludes a radial flange, and in that the radial flange is compressedbetween the closing member and the accommodating member for securing thesleeve in position in an axial direction. This measure is used to retainthe pump subassembly in the accommodating member, while the necessaryattaching forces are introduced into the sleeve at a point spaced fromthe seat of non-return valves, thereby preventing that the sealingeffect of the non-return valves is impaired.

In a favorable embodiment of the invention, the stepped bore has a borestep with a bore diameter that is designed larger than the radial flangeso that an exclusively axial abutment of the radial flange prevails.This prevents an application of force at the periphery of the sleevewhich causes out-of-true operation or deformations of the sleeve.

It is furthermore favorable that the sleeve includes a bowl-shapedportion which is used as a support for the resetting spring and has acylindrical wall and a bottom on which one end of the resetting springis abutting. This obviates the need for a separate assembly of aseparate spring retainer in the accommodating member.

A portion of the sleeve can be substantially V-shaped or U-shaped incross-section so that an indentation provided between the wall and acollar is used to accommodate the resetting spring, and an outsideindentation formed by the collar accommodates a non-return valve in sucha fashion that resetting spring, sleeve and non-return valve intersectat least in the area of the portion in a radial direction. Anarrangement of the components involved that achieves especially shortdimensions is thereby given, and a seat for a non-return valve can beprovided in the bottom area of the sleeve. The seat is preferablyprovided at the collar.

Centering of the spring is enabled when the collar in the seat area hasa substantially conical portion, the diameter of said portioncorresponding basically to the diameter of the resetting spring and theportion engaging the resetting spring. The conicalness facilitates theplacement in the event of an inexact feeding of components.

The mounting space requirement is furthermore reduced when the closingmember has a bowl-shaped design and includes a wall and a bottom, andthe bowl-shaped portion of the sleeve is accommodated in an inner spaceof the closing member, and an end surface of the wall maintains theradial flange in abutment on the bore step.

Essential parts of the piston pump, in particular the sleeve and theportion, due to the protuberances are formed as sheet-metal shaped partsbeing fastened in the area of the radial flange to the closing member bymeans of calked or pressed engagement.

In principle, the pump of the invention shows a good aspirationbehavior, even at low temperatures of the pressure fluid, because theconstruction allows correspondingly expanded aspiration cross-sectionsespecially as regards the channel routing and the piston configuration.

Further details of the invention can be taken from the followingdescription making reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a cross-sectional, enlarged view of a first and secondembodiment of a piston pump separated by an axle center;

FIG. 2 shows an enlarged view of a variant according to FIG. 1;

FIG. 3 shows a third embodiment of a piston pump;

FIGS. 4 a-c show details of different sleeves, which are principallybased on the embodiment shown in FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an assembly 1 with a schematically illustrated drive 2, inparticular an electric motor, which is flanged to an accommodatingmember 3 for electromagnetically operable valves, channels, accumulatoror damper chambers and to a piston pump 10. An electronic control unit 4(shown only schematically) is provided on an opposite side of theaccommodating member 3. The illustrated assembly 1 is in particular usedfor slip control or driving stability control in motor vehicles, yetsimilar or different cases of application are also feasible.

A preferably central stepped bore 5 of the accommodating member 3accommodates a sealed roller bearing 6 of the drive shaft 7 whose freeend is designed as an eccentric 8 projecting into a crank chamber 9 ofthe stepped bore 5. It is principally possible that the eccentric 8 isground out directly at the drive shaft 7 or motor shaft, or is designedas a separate component and attached to the drive shaft. For an extendedpump operation life the crank chamber 9 can be flooded with leakagefluid, especially with brake fluid, and a reservoir connected to thecrank chamber 9 is used for the fluid take-up within the drive 2, theaccommodating member 3 or the electronic control unit 4.

The eccentric 8 is equipped with a needle bearing 11 which is closed onone side by a bowl-shaped outside ring 12, the bowl bottom 13 thereof,with a wart-like projection, being movable into abutment on an endsurface of the drive shaft in a punctual manner and with low friction. Abottom 14 of the crank chamber 9 has a ball 15 so that the bowl bottom13 abuts with an outside surface remote from the motor shaft on the ball15 in a low-friction fashion, and the outside ring 12 that can berotated relative to the accommodating member 3 does not have any directcontact to the material of the accommodating member 3. This counteractsfrictional stress of the accommodating member 3, without having to applywear-resistant material coatings such as eloxal coatings onto walls ofan accommodating member 3 made of aluminum.

As shown in FIG. 1, two pistons 16, 17 of the piston pump 10 which arein each case of bipartite design are arranged and guided within astepped bore 64, 65, movable in a sleeve 18, 19. The pistons extend witha first hydraulic diameter a supply chamber 30, 31 and reach with an end20, 21 into the crank chamber 9 where they contact a periphery of theoutside ring 12. Another end 22, 23 of the pistons 16, 17 has another,second hydraulically active diameter and projects into a displacementchamber 24, 25. While the second end 22, 23 of the pistons 16, 17 issealedly guided by way of a sealing and guiding ring 26, 27 in thesleeve 18, 19, another guiding and sealing assembly 28, 29 allowsarranging the supply chamber 30, 31 between the mentioned sealingassembly 28, 29 and a non-return valve 32, 33 acting as a suction valve.From a pressure fluid inlet E the pressure fluid propagates via achannel and a filter 34, 35 arranged at a sleeve into the supply chamber30, 31. During the aspiration stroke, pressure fluid is conveyed intothe displacement chamber 24, 25, with the non-return valve (suctionvalve) 32, 33 open, and during the displacement stroke it is conveyedinto a pressure fluid outlet A, with the non-return valve (pressurevalve) 36, 37 open. It must be added that the effective hydraulic pistondiameter in the displacement chamber 24, 25 along with the hydraulicallyeffective diameter in the supply chamber 30, 31 permits improvedaspiration properties in the event of viscous pressure fluid. Furtherdetails of the piston pump will be explained by way of FIG. 2 showingthe left-hand part of FIG. 1 on an enlarged scale.

As can be seen, the stepped end of the piston 16 which is also splitlike a fork by at least one groove has a plate-shaped valve seat 38whose cylindrical wall portion 39 is slipped at least partly onto theend 22. It also carries the guiding and sealing ring 26 on an outsidesurface. The valve seat 38 includes a stop 40 to secure the sealing ring26 axially in position. A component 42 which acts additionally as aspring plate for a piston resetting spring 41 and a valve spring 45 or,like in FIG. 2, a separate spring plate abuts in the shoulder area ofaxially bent legs 43 on a front side of the valve seat 38. Radial legs44 can abut flatly on the sealing ring 26 in an axial direction so thatthe sealing ring is fixed in position on the piston 16 and oscillateswith it in relation to the accommodating member 3. As is further shownin FIG. 2, the legs 43 of the component 42, which point in the axialdirection, can engage into a slot between the cylindrical wall portion39 of the valve seat 38 and the sealing ring 26, whereby the radialcounter pressure of the sealing ring 26 on the sleeve 18 can beincreased. A cylindrical component portion 46 prevents the valve spring45 from bulging.

The piston resetting spring 41 extends through the entire displacementchamber 24 and bears with one end on an abutment 47 that is remote fromthe piston and also serves as a bottom for the sleeve. According to theembodiment of FIG. 1, the sleeve 18 is shaped like a bowl, and thesupport 47 is configured as a component bulged like a plate and having aradial flange 48, a wall 49 and a bottom area 50. As becomes apparent,the radial flange 48 abuts flatly on a radial flange 51 of the sleeve18. While the wall 49 is bulged cylindrically in the direction of theclosing member 52, the bottom area 50 includes a collar 53 which pointsoppositely, that means in the direction of piston 16, and has a seat 54for a valve member 55 of the non-return valve (pressure valve) 36.Consequently, a bulge provided between collar 53 and wall 49 on the sideof the displacement chamber is used to accommodate the resetting spring41, and a bulge formed by the collar 53 itself is used to accommodateessential parts of the non-return valve 36 such as valve member 55 andvalve spring 56 in particular. The mentioned components are hencearranged in each other in such a fashion that they intersect at least inpart in a radial direction, what results in mounting space economy. Asbecomes further apparent from FIGS. 1 and 2, the collar 53 has a largelyconical form. Its (outside) diameter initially corresponds substantiallyto the (inside) diameter of the resetting spring 41, subsequentlytapering in the direction of seat 54. This arrangement improves thecentering of the resetting spring, in particular during the assembly.

Various measures are possible to support the valve spring 56 of thenon-return valve 36. As can be seen in FIG. 1 by way of the embodimentin the right-hand half of the drawing, the valve spring 56′ can besupported axially directly on the closing member 52′, and asubstantially plate-shaped retaining component 57′, the shape of whichcomes close to the shape of the support, is provided with a guidingportion 58′ for the valve spring 56′. A radial flange 59′ of theretaining component 57′ comprises edge portions 60 being bent in such afashion that they embrace the radial flange 51, 48 of sleeve 19 andsupport 47′ in order to fix an independently operable modular unitcomposed of sleeve 19, resetting spring 41, non-return valves 33, 37 andthe retaining component 57′. According to a modified embodiment, as canbe taken from FIG. 1 in the left-hand half of the drawing (as well asfrom FIG. 2 on an enlarged scale), it is possible that the retainingcomponent 57, in addition to the guiding portion 58, includes a stop 61for the valve spring 56. Finally, in a simplified variant according toFIG. 3, the retaining component 57 may be omitted because the valvespring 56″ abuts axially on the closing member 52″ and the latterincludes either a dome-shaped elevation 62, 63 or an elevation 64, 65shaped like a socket, as is shown in dotted lines in FIG. 2. In theevent of rationalization of the separate retaining component 57, theindependently operable unit is manufactured in that the closing member52″ is calked with the radial flange 48, 51, as can be seen in FIG. 3.

In all embodiments the sleeve is retained by a closing member 52, 52′,52″ in the stepped bore of the accommodating member 3. For this purpose,the closing member 52, 52′, 52″ is calked or clinched with theaccommodating member 3, as is shown in the Figures. A clinchedengagement implies in this context that the closing member 52, 52′, 52″is made of a material harder than the accommodating member 3, and thatthe closing member 52, 52′, 52″ in the area of a bore wall is furtherprovided with a contour producing a form lock by means of cold workingbetween the components involved in the event of a relative displacementbetween closing member 52, 52′, 52″ and accommodating member 3.

In order to integrate the closing member 52 into the independentlyoperable pump assembly even in the type of construction according toFIG. 1, it is possible that it has a substantially concave design foraccommodating parts of the pump cartridge (comprising sleeve 18, 19,non-return valves 32, 33, 36, 37), resetting spring 41, piston 16, 17)and includes a wall 66 with an end surface 67 and a bottom 68, while theinside contour has a profiling or fit receiving the retaining component57 in a clamping manner. This achieves a space-saving, yeteasy-to-assemble arrangement. However, provisions must be made to ensurethat there is a sufficient flow cross-section for the pressure fluid.

FIGS. 3 a to 3 c show design variants of a sleeve 18, which ispreferably manufactured by deformation and which includes a radialflange 51. In general, the basic idea of the invention renders itpossible to shape essential parts of the pump cartridge, in particularits sleeve 18, 19, including bottom (support 47) as sheet-metal shapedparts or punched parts, without having to fear functional impairment inthe area of the non-return valves 36, 37 due to deformations caused bythe assembly. This is because starting from the closing member 52,retaining and pressing forces are mainly introduced only into a radialflange 51 of the sleeve 18, 19, from which these forces are thenconveyed into a bore step 69 of the accommodating member 3. Basedthereon it is possible to impart a one-part design to the sleeve 18 c bymeans of deformation according to FIG. 4 c, or to make it up of severalparts, as is illustrated in FIGS. 4 a, b. In this arrangement, thecomponent forming the bottom or support is molecularly interfaced withthe tubular guiding portion of the sleeve 18 a,b, and the radial flangecan be provided at the bottom according to FIG. 4 a, or at the guidingportion according to FIG. 4 b, without departing from the spirit of theinvention. In all three cases, however, there is calking engagementbetween closing member 52 a,b,c and radial flange 51 a,b,c, as has beendescribed already with regard to FIG. 2.

LIST OF REFERENCE NUMERALS

-   -   1 assembly    -   2 drive    -   3 accommodating member    -   4 control unit    -   5 stepped bore    -   6 roller bearing    -   7 drive shaft    -   8 eccentric    -   9 crank chamber    -   10 piston pump    -   11 needle bearing    -   12 outside ring    -   13 bowl bottom    -   14 bottom    -   15 ball    -   16 piston    -   17 piston    -   18 sleeve    -   19 sleeve    -   20 end    -   21 end    -   22 end    -   23 end    -   24 displacement chamber    -   25 displacement chamber    -   26 guiding ring    -   27 guiding ring    -   28 sealing assembly    -   29 sealing assembly    -   30 supply chamber    -   31 supply chamber    -   32 non-return valve    -   33 non-return valve    -   34 filter    -   35 filter    -   36 non-return valve    -   37 non-return valve    -   38 valve seat    -   39 wall portion    -   40 stop    -   41 resetting spring    -   42 component    -   43 leg    -   44 leg    -   45 valve spring    -   46 component portion    -   47 support    -   48 radial flange    -   49 wall    -   50 bottom area    -   51 radial flange    -   52 closing member    -   53 collar    -   54 seat    -   55 valve member    -   56 valve spring    -   57 retaining component    -   58 guiding portion    -   59 radial flange    -   60 retaining portion    -   61 stop    -   62 elevation    -   63 elevation    -   64 stepped bore    -   65 stepped bore    -   66 wall    -   67 end surface    -   68 bottom    -   69 bore step    -   E inlet    -   A outlet    -   Ax axial direction    -   R radial direction

1-9. (canceled)
 10. A piston pump (10) for supplying pressure fluid fora controlled vehicle brake system, including the following features: apiston (16, 17) is movably arranged in a stepped bore (64) of anaccommodating member (3) provided with a closing member (52); the piston(16, 17) is guided in a sleeve (18, 19) at least in sections; the sleeve(18, 19) comprises a non-return valve (32, 33, 36, 37) which is arrangedcoaxially to the piston (16, 17) and is used for the ventilation of aworking chamber (24, 25) into which the piston (16, 17) plunges; aresetting spring (41) is provided within the sleeve (18, 19) between asupport (47) and the piston (16, 17), wherein the sleeve (18, 19)includes a radial flange (51), and wherein the radial flange (51) iscompressed between the closing member (52) and the accommodating member(3) for securing the sleeve (18, 19) axially in position.
 11. The pistonpump as claimed in claim 10, wherein the stepped bore (64) has a borestep (69) with a bore diameter designed to be larger than the radialflange (51) for an exclusively axial abutment of the radial flange (51).12. The piston pump as claimed in claim 10, wherein the sleeve (18, 19)includes a bowl-shaped portion which is used as a support (47) for theresetting spring (41) and has a wall (49) and a bottom area (50) onwhich one end of the resetting spring (41) is abutting.
 13. The pistonpump as claimed in claim 12, wherein the portion of the sleeve (18, 19)is bulged to be substantially V-shaped or U-shaped in cross-section sothat an indentation provided between the wall (49) and a collar (53) isused to accommodate the resetting spring, and wherein an outsideindentation formed by the collar (53) accommodates a non-return valve(36, 37) in such a fashion that resetting spring (41), sleeve (18, 19)and non-return valve (36, 37) intersect each other at least in the areaof the portion in a radial direction R.
 14. The piston pump as claimedin claim 12, wherein the collar (53) in the seat area has asubstantially conical portion, the diameter thereof correspondingbasically to the diameter of the resetting spring (41), and wherein theportion engages the resetting spring (41).
 15. The piston pump asclaimed in claim 12, wherein the closing member (52) has a bowl-shapeddesign and includes a wall (66) with an end surface (67) and a bottom(68), and wherein the sleeve (18, 19) at least with the support (47) isaccommodated in an inner space of the closing member (52), and whereinthe end surface (67) retains the radial flange (51) in abutment on thebore step (69).
 16. The piston pump as claimed in claim 10, wherein aseat (54) for a non-return valve (36, 37) is provided in a bottom areaof the sleeve (18, 19).
 17. The piston pump as claimed in claim 16,wherein the seat (54) is provided at the collar (53).
 18. The pistonpump as claimed in claim 16, wherein the sleeve (18, 19) and inparticular the support (47) are designed as sheet-metal shaped parts,and wherein these are fastened in the area of the radial flange (51) tothe closing member (52) by means of calked or pressed engagement.